There are two methods of urine drug testing, used in laboratory analysis in our days:
Urine immunoassay
The method of urine immunoassay helps to screen urine for the presence of the following classes of narcotics: opiates, marijuana, amphetamines, barbiturates, cocaine, ephedrine, benzodiazepines, phencyclidine, nicotine, extasy and some others.
Method of urine drug testing
The testing liquid absorbs though the special absorbing facility, and in case of containing the parent drug or its metabolites, it reacts with specific antibodies and forms antigen-antibody complex. This complex enters into competitive antigen binding reaction in test zone (“1” – “5”) of a test strip. If the concentration of narcotic in the sample is higher than the threshold level, a pink stripe doesn’t appear. If the narcotic substance is absent or its concentration is lower than the threshold level, the antigen, immobilized in test zone of the strip, reacts with second antibody, resulting in a pink stripe appearing in this area. Unreacted components of the test bind together in control zone, forming a pink stripe. The pink stripe in control zone indicates the correctness of performed test and proves the diagnostic activity of test components.
The negative drug test makes 2 pink stripes in test zones appear; this way the test indicates the absence of narcotic substances in urine sample or proves that its concentration is lower, than the threshold level.
The positive drug test result indicates only 1 pink stripe in control zone, saying about presence of drug substance.
Urine test strips are not meant for identifying the drug quantity in urine or the level of drug intoxication.
Drug testing procedure
The testing procedure and its results depend on a client to be tested and a place of testing. In general terms the procedure is going the next way:
The tested urine is to be collected into a dry cup with a maximum capacity of 50 ml. It should be analyzed at once after collection. The result can be received in 10-15 minutes.
In case of positive drug test, the result is to be formalized in “The urine drug test by immunoassay data sheet”.
Urine drug testing by chemico-toxicological analysis
Here belong:
1) Fluorescence polarization immunoassay (FPIA) of urine for one of the following groups: opiates, methadone, cannabinoids, amphetamines, cocaine, barbiturates, phencyclidine, benzodiazepines;
2) Enzyme immunoassay (EIA) of narcotic and psychotropic substances in urine for the group of narcotic and psychoactive substances (opiates and other groups);
3) Urine drug test by chromatography-mass spectrometry;
4) Urine alcohol test by gas-liquid chromatography.
The urine collecting has its own peculiarities. Urine must be collected in conditions, excluding the possibility of replacement or falsification of biological object.
The test-taker collects his urine (from 30 ml up to 100 ml) into graduated vessel made of glass or plastic, with wide neck and volume up to 200 ml. He gives the vessel with urine to the specialist, responsible for urine drug testing. The vessel with urine is to be covered with cover plate (cover).
By sending urine for chemico-toxicological analysis for alcohol, its surrogates and metabolites presence, it ought to be taken out of container and placed into clean dry bottle vol. 10 ml in quantity of no less than 5 ml, then closed by flip-off cap and sealed.
Taken for chemico-toxicological analysis for presence of alcohol and its surrogates, narcotic, psychotropic and other toxic substances causing intoxication, the urine ought to be delivered to the laboratory within 48 hours after having been collected. Before sending off, the urine is kept in refrigerator at temperature 0-2 degrees Celsius.
After that the urine provided with supporting documents is delivered in packed and sealed containers in analyses carrier by the specialist, responsible for tests delivery.
Urine drug tests performed with the help of chemico-toxicological analysis allow the specialists to prove the fact of drug abuse within 72 hours of using narcotics. In some cases it may be possible to indicate the quantity of narcotic per unit volume of urine. Such urine drug testing is not to be a quick test. The tested urine needs to be delivered to the laboratory and tested with the help of laboratory reagents and special equipment.
The results of urine drug test, performed by the method of chemico-toxicological analysis, are considered a legal fact and can be used in the court as evidence.
